NOAA Fisheries, Southwest Fisheries Science Center, La Jolla, CA, United States of America.
Institute of Marine Sciences, University of California, Santa Cruz, CA, United States of America.
PLoS One. 2022 May 26;17(5):e0269069. doi: 10.1371/journal.pone.0269069. eCollection 2022.
Despite their broad distribution across the North Pacific Ocean, the only known spawning grounds for Pacific Bluefin Tuna (Thunnus orientalis) are around coastal Japan and the East China Sea. However, an increase in the prevalence of large bluefin tuna up to 10 years old in the California Current System during exceptionally warm ocean conditions has led to speculation that they may be spawning in this region. To investigate this possibility, we collected samples from 36 females (estimated 3-8 years old) between 2015 and 2019. Histological analyses revealed no signs of imminent, active, or recent spawning. Further examination of historical ichthyoplankton collections showed no records of larval bluefin tuna, but confirmed the presence of the larvae of other tuna species in waters > 24°C. Fishery-dependent records showed that bluefin tuna are rarely recorded in purse seine catches where surface temperatures exceed 23°C. Our study, therefore, provided no evidence of bluefin tuna reproduction in the CCS. However, more comprehensive sampling, in particular off southern Baja California, may be required to confirm the absence of spawning.
尽管太平洋蓝鳍金枪鱼（Thunnus orientalis）广泛分布于北太平洋，但已知的唯一产卵场是日本沿海和东海。然而，在异常温暖的海洋条件下，加利福尼亚海流系统中出现了大量 10 岁以下的大型蓝鳍金枪鱼，这引发了人们对它们可能在该地区产卵的猜测。为了研究这种可能性，我们在 2015 年至 2019 年间采集了 36 条雌鱼（估计 3-8 岁）的样本。组织学分析显示没有即将、活跃或最近产卵的迹象。对历史上的浮游生物采集的进一步检查没有记录到幼蓝鳍金枪鱼，但证实了在水温超过 24°C 的水域存在其他金枪鱼物种的幼鱼。渔业相关记录显示，在表层水温超过 23°C 的情况下，金枪鱼很少被围网捕获。因此，我们的研究没有提供在 CCS 中蓝鳍金枪鱼繁殖的证据。然而，可能需要更全面的采样，特别是在南下加利福尼亚半岛附近，以确认是否存在产卵。
